Redmine

When I copy & paste or upload a 32 bit depth image into issue, ref it using !! format, and export to pdf file, the image can not display in the file, just leave a large blank area.
But a 24 bit depth image goes right.

system information as follow:
Environment:
Redmine version 5.0.5.stable
Ruby version 3.0.2-p107 (2021-07-07) [x86_64-linux-gnu]
Rails version 6.1.7.2
Environment production
Database adapter Mysql2
Mailer queue ActiveJob::QueueAdapters::AsyncAdapter
Mailer delivery smtp
Redmine settings:
Redmine theme Circle (includes JavaScript)
SCM:
Git 2.34.1
Filesystem
Redmine plugins:
accept 0.0.3_2
additional_tags 1.0.7
additionals 3.0.8
issue_charts 1.3.0_3
redmine_dashboard 2.14.0
redmine_dmsf 3.1.1
redmine_importer 1.2.2
redmine_indicator 0.2.16
redmine_lightbox 1.0.2
redmine_logs 0.3.0
redmine_searchable_selectbox 0.1.10