Data still present in backup / on disk after table delete or/and import from sql

Most probably it's a setting I am missing, but I cannot find any answer nowhere.

Everything started with some unusual messages in mariabackup log like:
[00] 2024-04-05 02:48:02 mariabackup: Generating a list of tablespaces
[00] 2024-04-05 02:48:02 DDL tracking : create 241 "./racktables/innodb_test.ibd"
[00] 2024-04-05 02:48:02 DDL tracking : delete 241 "./racktables/innodb_test.ibd"
[00] 2024-04-05 02:48:02 DDL tracking : create 242 "./racktables/innodb_test.ibd"
[00] 2024-04-05 02:48:02 DDL tracking : delete 242 "./racktables/innodb_test.ibd"

those are probably some temp tables created by racktables web app

but also, on a simple and usual mysql racktables < racktables.sql (so a simple import with drop/create table) the backup log on next day there were full of that kind of messages, and also the space on disk was doubled, also backup space; it's like those tables we're "kept", even they we're dropped

after restarting mysql everything was clean, next day backup was as usual

I'm using innodb_file_per_table = ON

even migrations from a php framework cause the same behavior, all DDL operations remain "somewhere"

mariadb versions:
10.11.6-0+deb12u1
10.5.23-0+deb11u1