Note the pattern:
2021-02-23T08:35:08.249856Z 18 [Note] Aborted connection 18 to db: 'dbname' user: 'root' host: 'localhost' (Got timeout reading communication packets)
Large time gap
2021-02-23T10:34:19.443803Z 0 [Note] InnoDB: page_cleaner: 1000ms intended loop took 5088ms. The settings might not be optimal. (flushed=201 and evicted=0, during the time.)
innodb_buffer_pool_size=27G is too close to the limit especially with a large amount of (max-)connections.
Lower this down and examine utilization. show global status like 'innodb_buffer_pool_pages% should be full after a reasonable amount of warmup (24hrs+)
show global status like 'innodb_buffer_pool_read%. read_requests vs reads should be quite large. (...