hi,
that version of rclone is years old, the lastest rclone is v1.59.0,
tho you mention that the issue might be system updates but might want to take a read of
https://forum.rclone.org/t/rclone-mount-random-slow-speeds/31417
this is a set of optimized parameters.
https://github.com/animosity22/homescripts/blob/master/systemd/rclone-drive.service