This is an incompatibility; I'm not sure if the behavior would also be considered a bug.
Given the following code:
Lucee automatically "corrects" and encodes the URL, redirecting to: test.cfm?place=subsystem%3Asection.item
ACF leaves the provided URL unaltered, redirecting to: test.cfm?place=subsystem:section.item
The colon : is the default subsystem delimiter for FW/1 applications and we encountered this while porting an ACF application to Lucee.
While the encoded version of the URL may be correct according to the spec, Lucee's automatic altering of developer input here was surprising and could result in unexpected behavior. In our case, the introduction of capital letters in the percent encoded portion of the URL caused problems with rewrite rules.