[1] https://openacs.org/forums/message-view?message_id=5380070 [2] https://openacs.org/webpush-demo/webpush-demo.tcl
I compiled Naviserver 4.99.17 with Tcl 8.5.19 to see if the issue resolved itself, and I am not getting the same result as your example.
It does appear the Naviserver version affected the results, and not the Tcl version.
all the best -g