Form Analytics doesn't cleanup its old form_field/form_page log data

I’m using Matomo (3.14.0) with Form Analytics (3.1.28). Both “delete old raw data” and “delete old aggregated report data” policies are in place (with core:archive cron job). Still, in practice, I see that Form Analytics purges records from the log_form db table only, leaving log_form_field and log_form_page tables filled with all the historical data from the beginning of time.

Here is my table size summary:

MySQL [matomo-prod]> SELECT TABLE_NAME AS `Table`, ROUND((DATA_LENGTH + INDEX_LENGTH) / 1024 / 1024) AS `Size (MB)` FROM information_schema.TABLES WHERE TABLE_SCHEMA = "matomo-prod" ORDER BY (DATA_LENGTH + INDEX_LENGTH) DESC limit 11;
+------------------------------+-----------+
| Table                        | Size (MB) |
+------------------------------+-----------+
| matomo_log_form_field        |      9185 |
| matomo_log_form_page         |      1405 |
| matomo_archive_blob_2020_06  |      1195 |
| matomo_archive_blob_2020_08  |      1101 |
| matomo_archive_blob_2020_05  |      1093 |
| matomo_archive_blob_2020_07  |      1039 |
| matomo_log_action            |       704 |
| matomo_log_visit             |       641 |
| matomo_log_link_visit_action |       363 |
| matomo_archive_blob_2020_09  |       200 |
| matomo_log_form              |       116 |
+------------------------------+-----------+

I can confirm that old records are correctly purged from log_form but not from log_form_page/log_form_field tables, matching them by idvisit/idlogform. How can I clean that old data and prevent its accumulation in the future?