Someone asked about flare with the EF to E adapter in another thread.
This morning I took A7II, both adapters and Canon 24mm TSE lens into front courtyard and did a test.

Camera was set to ISO 200, Av shutter. It was on a tripod and I used cable release for shutter.

I ran through all the F stops but am only linking to the F3.5 set here. Mainly because it seems that's where the flare is most likely to appear.

The scene includes sky, sunlit white brick (slight clipping indication here in LR) as well as some deep shadows amongst the plants to camera right.

I shot first with Fotodiox adapter, then with Metabones IV, and finally with Metabones IV while flagging the lens above and left since that's where the highlights and sky were in the scene.

To accommodate faster thread loading I am linking to reduced sized JPGs with a link below each to the full sized camera generated JPG. (The reduced sized jpgs were generated using the Lightroom export function.)

I looked at the images at 1:1 and can't find any indication of flare caused by the adapters.

I noticed when using the metadata function in Lightroom Library that the camera assigns ZA to the 24 TSE when mounted on the Fotodiox adapter and GII when the lens is mounted on the Metabones adapter.

Fotodiox Adapter:

Full sized camera JPG

Metabones IV adapter:

Full sized camera JPG

Metabones IV adapter with flag:

Full sized camera JPG