I have heard some people say that Philips SOX lamps made at Hamilton in the last few years (2018-2021) had some serious quality control issues and would fail after only a short time of being in service. I have even heard some people saying that Philips intentionally sabotaged the lamps made during that time to try to get people to switch to other light sources (like LED).

Can anyone speak from experience and prove or disprove this theory about the quality of some of the last SOX lamps that Philips made?

There was an interesting technical discussion with James about dark barium getter bands around the cathodes of last Philips SOX lamps. Probably no one sabotaged intentionally, but as product line goes into obsolescence and is prepared to be axed, management becomes reluctant to invest any more money to keep manufacturing level, and also quality control begins to slip. That does not happens only with lamps, as you may have noted multiple times, the same happens with most other products in the course of their lifetime...

another issue that often crops up as soon as you ANNOUNCE a production change / termination to your suppliers they often will stop production of components "early" to be able to retool and pickup a replacement contract order
and it is not unheard of for component suppliers having to restart production OR outsource if they fall short of expected orders and understandably the supplier is NOT overtly concerned on quality as they already "lost" the contract

In those years, Philips was right in the process of (and/or just shortly after) spinning off their lighting division into Signify. Reorganisations are often a source of demotivation and a loss of instititional knowledge from a company, reducing plant efficiency and output quality.

I reckon for Signify, who of course see the future of lighting as 100% solid state, the legacy hot glass stuff is a major liability. Anything made out of glass - save for a few specialty specialty lamps - is in decline. So i reckon that they wanna get rid of the expensive old folks with the knowledge about specialized glass making ASAP.

It's highly likely that the folks working in the factory see such things coming from miles away and start to slack off a bit, because they know that putting any energy into maintaining the production lines in good condition might be energy that's completely wasted.
No one is gonna bother putting in the energy to absolutely perfectly dial in the decades old machines, when rumors start to circulate that the plant will be shut down anyway. So eventually only the bare minimum is done to keep the lines running for just another couple of days, and another couple of days, and another couple of days until the stop production order arrives. 

So in short - any decline in quality is likely caused by a series of different factors, for instance knowing that the end is near anyway and losing institiutional knowledge in the reorganisations. Actual sabotage is unlikely.
It's pretty similar to what happened with the final series of TV CRTs which were highly mediocre in quality.

I started wondering the same thing after looking at my 2 18w Philips Master SOX-E lamps which are the same age and both NOS from what I know.

Here's a photo of my 18w lamps and you can see the difference.

The bottom lamp looks how I'd expect a new SOX lamp to look. Clean tubes with minimal blackening. This lamp appears to have been powered once, likely at the factory for a test run or quality check however the top lamp looks like it's almost at EOL with the tubes showing significant blackening around the electrode coils.

James has actually covered this exact topic on here somewhere, and no they didn’t, the same manufacturing processes were followed to the letter, right up to the very last lamp.
But this phenomenon wasn’t exclusive to just Philips, GEs last SOX were also plagued with the same quality issues giving some lamps just a few months in service until things started to go wrong!

Now the last LPS from Osrams Shaw factory on the other hand didn’t suffer with any quality issues that I’m aware of?

In fact, you probably did not get the idea of what James said completely. I asked why newer Philips lamps had that unsightly black sputtering 'socks' at discharge tube ends. James reply was that it is some barium intentionally sputtered from the filaments for the getter action, BUT in the earlier lamps a special machine with a photo control was used to dose a precise amount of barium sputter at that process stage. When machine got broken, management decided not to bother to restore it, and instead excess amounts of barium was sputtered on the fixed time. That's why that black socks on the new lamps, and yes, technology was intentionally degraded...


 

Well no, you’re just referring to your post on the barium question, the quality question was raised in the discussion about the end of SOX manufacturing back in a 2019 post.
This is where James had stated the same quality had been adhered to right to the end of the last day of production.

From 2018ish on the T8s have not been very good either.  Much shorter life, across all 3 brands.  For buildings I have been relamping fixtures that were changed out just a few years ago, when they would previously go 6+ years.  Be it on new or older ballasts. 

Are those standard T8s or the extended life XL lamps?  Are they experiencing cathode failures, mercury starvation, or gas contamination?

Standard.  I've not installed any XL since before 2018. They are going EoL much quicker.  The Philips weak cathodes are not quite as bad on the newer tubes, surprisingly.  Not seeing mercury starvation quite as much on the GEs and Philips as they were prone to in earlier years.  They are just getting black ends quicker and going EoL. 

I would not say they have sabotaged the last of the Philips SOX lamps. In my experience their SOX lamps especially 55w and 90w have always varied massively in how long they last. Some of them especially 2010 onwards can do anything between 6 months and 7 or 8 years. 2012 13 14 and 15 seemed to be the worst years with lamps of the above wattages doing just a year or two in service and the odd one doing 4-6.

35w i have always known to last quite well. Same with the 135w lamps if the caps did not burn out.

The philips lamps have always been worse than the Osram or Radium lamps that philips made for them! But i have heard that them lamps were made to Osram / Radium spec by philips which is why they lasted a lot longer. Those were doing 6-9 years in all wattages