OP said:
"sounding quite great until recently. Recently ... wonderful."
everything was fine, in his environment that did not change, thus it isn't the carpet or the way OP yanked his LPs out of the sleeves.
the platter mat was fine, was in play when it sounded great.
"Very quickly I started noticing some very loud pops (almost electric sounding)."
minor even consistent static does not make loud pops.
the new LP was a mess, but it was properly cleaned, , and subsequently cleaned.
If previously great sounding LP's now have problems, something changed, WHAT?
stylus AND cantilever full of gunk from the new problematic LP?
considering nothing changed until the new 'slimy' lp was played: what else could have changed?
lastly: always ask: misled by inadvertent coincidental timing of a different source of the problem?