False flag frameshift variant prediction ?

[pelotbdr]

Hello, I'm trying to understand the output I got for a site with multiple alleles (REF: ACCG ALT: GCCA,GCCG)

It was classified as a frameshift variant despite the variants having the same number of nucleotides as the reference. Here is an excerpt of the INFO column for this variant:

frameshift_variant&missense_variant | HIGH | MITF | MITF | transcript | XM_034440584.1 |protein_coding | 11/11 |c.1518_1521delCGGTinsTGGC"

Is this a misclassification/bug ?