guitar tab slur crossing?

Indeed, I think it's already reported in a different way. I see the manifestation of two things. I try to summarize.

1) By entering notes in the standard staff, it occurs only in this direction, ie: from bass to treble. And exactly at the moment when the Bb is entered, which switches on the fifth string (fret 13), fault of possibility on the third string, already occupied by the G.

And we know this case. See here:limitation: https://musescore.org/en/handbook/known-limitations-musescore-2.0, paragraph "Note input", Tablature staff linked...)

By typing the notes in reverse, treble to bass, this question does not appear.

2) We can duplicate this behavior, by entering the notes via the Tab staff. So, I see the intervention of this second issue (related, I guess likely): #98816: Wrong tie direction in chords related to the pitch of two adjacent strings in Tabs

For example, enter the number 13 (Bb3), then 0 (D3), and add a tie. You get the described result:

Indeed, by entering these numbers, you have a superposition of two notes (Bb3, so higher pitch than -> D3) on adjacent strings, so as a re-entrant tuning, like a ukulele (G4, fourth string -> D4, third string)

Just change eg the pitch of the fifth string in the "String Data" (A to Ab), and the issue disappears because the new chord is again in a “logical” order (not re-entrant)