Subject character length limited to 255 in side conversation used in Macro

Hi, I was using macro for side conversation where I have used subject line with 900 characters using some placeholders and if-else logic to send an email to backoffice team with required format in subject which was working fine. 

3669;test@example.com;710;19;Investor;Investor;Smith;September 16, 2024;Call

Today, when I was trying to add one more field in subject line and then observed that it's not allowing me to use more than 255 characters in the code added to subject. This has a severe impact on my solution. 

However if I try using side conversation using trigger then I do not see limitation to subject length.

Please suggest how can I achieve the same.