Projectiles will only despawn like arrows when they hit a block thus if you get a lot of arrows inside a bubble column, you can create server/client lag or even crashes down the road.
While I understand this change could be controversial due to some players liking the ender pearl machines but this has to be fixed at least if there is a lot of them due to the number of lookups the entities do and can be exploited on servers and has been on 1.14.4.
Thank you for your report!
We're actually already tracking this issue in MC-125757, so I resolved and linked this ticket as a duplicate.
If you would like to add a vote and any extra information to the main ticket it would be appreciated.
If you haven't already, you might like to make use of the search feature in the future to see if the issue has already been reported.
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