mysqldump blocked on flush table

[christophe offroy]

Hi,
A long querie is running 30 minutes.
This querie do an insert from a view into a table.
Then when the mysqldump start , it is waiting on "Waiting for global read lock"
And a lot of queries are blocked too.

3238933 | backup | localhost | NULL | Query | 1189 | Waiting for global read lock | FLUSH TABLES WITH READ LOCK |
| 3238935 | pma | localhost:34606 | base | Query | 1191 | executing | INSERT INTO table base.INC_WORK_SNOW_LAST_STATUS_BUILDING ( column1 ) select column1 from base.v_snow_dernier_etat_connu |

How to prevent this issue and lock. Why mysqldump is waiting after an insert of a base.table when it backup a base2.table ?

mysql Ver 8.0.36-0ubuntu0.20.04.1 for Linux on x86_64 ((Ubuntu))
All my base are in MYIsam engine.

Thanks,
C.Offroy