I paid for a lifetime membership to Bumble premium a couple years ago, but as I noticed matches/likes declining for no apparent reason, I made a 2nd account with different credentials, paid for a week of premium, and had a bunch of matches (exact same profile as my other account).
From my anecdotal experience, they have some algorithm that leads to diminishing returns in order to keep extracting money for boosts or whatever.
I'm a digital nomad and changing locations frequently, so I have actually tried this A/B test a couple times when arriving in a brand new city. Same results.
The author pointed out in the article that users who join are shown to users who have been on the platform the longest and are thus more likely to provide likes because they are more desperate.
From my anecdotal experience, they have some algorithm that leads to diminishing returns in order to keep extracting money for boosts or whatever.