Currently (as of Carpet mod ac24a67 and Minecraft 1.17.1-pre1), when a repeating command block executes /script run with any valid script code and /carpet scriptsOptimization is turned on, the command block causes the script compiler to output the following line to the Minecraft Log every tick:

Input code size for system chat: # nodes, # deep

Both /carpet scriptsDebugging and /gamerule commandBlockOutput are turned off, but the message still gets printed to the Minecraft Log regardless. Whether that message gets printed could depend on either of the two above rules, or another Carpet mod rule.

dully noted