I'm playing with Minecraft Jave Edition 1.16.1 with this seed -649216996088098683, and i searched during maybe 90 minutes, and all end city i found (at least 10), none had an end ships. If there is end ships, did you reduce theur spawn rate?
I can confirm this bug with the Intel HD Graphics 5500. I have the same issue.
I just want to clarify that I do not lag when I play normally (but it is still necessary to improve the performance of the game...
Confirmed in 21w06a.