Dynamic Keyword Insertion & Quality Score
Yes, it can have an effect on the QS but generally it would be a positive move rather than negative. If you have the keyword appearing in the ad copy it's more likely the user is going to find it relevant and your CTR can go up. CTR is a big part of the QS.
On the other hand, if the ads don't make complete sense after the keyword has been inserted, the ad may read poorly and get a lower CTR.
Just make sure that the adgroups that are using them are set up in a way that if it was to happen all the time, the ads read well.
I hope this helps you but let me know if you have any other questions.
The safe way to use DKI is to apply it to an ad group with exact match keywords , this way only when the search term matches exactly the keyword, the keyword is inserted in the Ad and it can have a high CTR also because the DKI text will be written in bold. For 100 exact match keywords of similar products this way you do not have to write 100 different Ads.
Besides the CTR , the DKI method can also create trademark in Ads issues if a trademark keyword is used or if the combination of the default text with the inserted keyword matches a trademark name.