Issue 1412 described a situation with multiple buffers and byte variables.
Results are indeterminate and may cause issues when this occurs. Since there are existing rules that do this, it was decided for Suricata 8 that such usage will be - Flagged as an error when --strict-rule-keywords is used - Flagged with a warning message but permitted otherwise.
This ticket aims to resolve the indeterminate nature of the situation (see 1412) and provide full support for multi-buffer byte variables.