Spam tagging and spam threshold

Hi,

In the following software environment I have problems with spam tagging 
and spam threshold values:
FreeBSD13.0
amavisd-new-2.12.2,
perl5 (revision 5 version 34 subversion 0),
10.5.15-MariaDB (postfix 3.6.3,1; clamav 0.104.2,1; p5-DBD-mysql 
4.050_1)

amavisd-new working with SQL as suggested by README 
(https://www.ijs.si/software/amavisd/README.sql-mysql.txt)

It founds the spam policy by sql query, but the spam tag levels are 
always 0.
spam_tag_level=>"0", spam_tag2_level=>"0", spam_tag3_level=>"0", 
spam_kill_level=>"0",

I wrote a "check" perl script that reads the policy table values. Here 
the float values are displayed correctly (3.000 , 6.900, etc).
However, the amavisd-new log shows spam_tag_level=>"0", so I suspect a 
faulty value conversion for amavisd (and not due to p5-DBD-mysql, 
Mariadb or perl).

As a workaround, I changed the float type (spam_tag_level, 
spam_tag2_level, tag3 and kill_level) in the database to varchar and 
-for now- it seems fine. A bit bizarre, perhaps, but it (apparently) 
works.

I've been looking for a solution for weeks now, in articles and mailing 
lists, without success.
Does anyone have any suggestions? Is it a bug?

Best regards,
K