As Casimir et Hippolyte stated in comments, Javascript does not support p{L}
unicode character class.
You can create your own character class:
[a-zA-Z0-9à-?]
Demo
If you want to allow those characters but replace characters outside those ranges, negate the character classes:
[^a-zA-Z0-9à-?]
Demo
Or as pointed out in comments:
[A-zà-??-??-??-??-?ǎ-??-??-??-??-???-??-??-??-??-??-??-??-??-?]
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