While constructing the test innodb.autoinc_import for my proposed fix of MDEV-33277, I was surprised to find out that CHECK TABLE would modify the contents of .frm files. If you enable the commented-out CHECK TABLE statement in the test, it will fail because on the next server restart (in read-write mode) the TABLE_SHARE::mysql_version for all affected tables would be MYSQL_VERSION_ID, that is, the current server version. That is, the files that had been copied from mysql-test/std_data/autoinc_import*.frm had been modified by the CHECK TABLE statement.

I might understand this if the statement were CHECK TABLE...FOR UPGRADE, but even that command should in my opinion honour the parameter --read-only.