I would be surprised if it's that honestly. I think you said you don't notice it until after it's bottled. That really sounds like a weird infection. If it was go ferm, water etc.. it would stick out right away I would think.
Hmm yeah covid or long covid may have that effect.
A couple other ideas chloramines are not removed from RO may be worth using sodium bisulfite in your water.
Your description and onset though make me think of an infection though?
Always disappointing to dump all that hard work and patience.
Sounds like maybe a warm temp trend if the last few batches have had similar issues?
What do you do for water?
Brewed up a herfstbok, with my pouch of Andechs. I probably should have started this one a month ago...
Here is the inspiration.
https://www.jopenbier.nl/product/4-granen-bokbier-blik/
I would also recommend expanding their sales area too, at least to Denver.
On a good note the didn't make their label a hideous yellow and blue mistake. And they do sell in cans.
I think it matters depending on what equipment you are using. I condition the malt and then double mill. That gets me the best flow in my Braumeister all in one.