Ty!

Short answer: No.

Longer answer: There is no algorithm on Lemmy or Fediverse generally. The (edit: local subscribed) feed pulls from all communities you’re subscribed to. All sort options (new, active) don’t boost any community over any other*, so abandoned communities should have no effect on what you see in your feed - they simple won’t contribute to it, if you’re viewing recent content.
The exception is the “scaled” sort option, which boosts smaller communities, I believe