I think it's not 'normal'. An ZM lens is primary dedicated to the Zeiss Ikon ZM system ... They should sell two diffrent variants for film and for digital.
I sent a request to Zeiss Germany to see what they say.... I think they should and must replace the mount for free!
here's my reply from Zeiss Europe:
"On analogue M mount cameras (e.g. Zeiss Ikon camera), there are no corresponding framelines in the camera´s finder that correspond with the angle of view of a 25mm lens. So it does not matter which framelines are switched automatically by the lens. An external viewfinder is always necessary to see the correct angle of view.
In digital M mount rangefinder cameras (e.g. Leica M8, M8.2), there are framelines that correspond with the angle of view of a 24mm lens. So the Biogon T* 2,8/25 lenses that have been optimized for the M8/M8.2 camera are equipped with a bayonet mount that engages the 24/35mm framelines in the viewfinder of this camera.
Because many of the Biogon 25mm lenses are used on a digital rangefinder camera, the bayonet mount rings had been exchanged on some of them.
On request, we can exchange the bayonet mount ring of each ZM lens for engaging any of the available viewfinder framelines. The price for this service is 60,- Euro (plus shipping plus VAT).
Please note that the Zeiss Ikon camera is not equipped with framelines that correspond with any lens below 28mm focal length! So we strongly recommend the use of the external clip-on viewfinder with 25/28mm framelines:
https://photo-shop.zeiss.com/en/Products/1365-664
Best Regards"
I don't have a digital Leica to corroborate their statement about the 24/35 frameline...I did ask for getting it fixed, but decided not to send it to Germany because I didn't want to pay 60+ Euros (shipping, insurance, wait, etc)
See if you can get the place where you bought your lens from to intercede
good luck