Tab-completed command/argument suggestions are re-suggested when tabbing after completing and hitting escape (see attached video).
Steps to reproduce:
Type (not run) any command incompletely, such as `/exe`.
`execute` is suggested. tap tab to complete and `cute` will be appended.
Tap escape to visually remove the listed suggestion(s).
Tap tab again to suggest completions again and tap tab yet again (effectively tapping tab twice); `cute` will be appended again.
Repeat steps 3. and 4. periodically, `cute` will be appended/suggested endlessly.
This appears to be a duplicate of MC-124817, which hasn't yet been resolved. If you have any additional information to provide regarding this issue, feel free to comment on the parent ticket. If you feel that this issue is affecting you, feel free to vote for the duplicated ticket, to give Mojang a basic idea of how many people are impacted by the problem. Just to further inform you, this will not determine how quickly the bug gets handled or fixed.