It is being said that director Zack Snyder was actually sacked from both Justice League and the DC Extended Universe (DCEU) several months prior to his official announcement of taking a break from work to process the death of his daughter, Autumn Snyder, last year.
The claim has been made by Josh L. Dickey, a former reporter for Mashable and who is ending his career as an entertainment journalist. Taking to Twitter earlier today, he cited his own article from back then and stated that he could not explicitly reveal all of the facts at the time.
It is further implied that Warner Bros. has not barred Snyder from its future plans of expanding the DCEU into new horizons. However, he will no longer be given any significant level of creative influence. In that light, Snyder is pretty much done with the franchise unless otherwise.
Since I'm shifting into DGAF mode, here's a hot one for ya: Zack Snyder was fired from the DCEU just over 1 year ago. Couldn't write it ~quite~ that way at the time, but was able to tapdance around it [clumsy/oblique headline not mine] https://t.co/7cht70rCaG
— Josh L. Dickey (@JLDlite) February 10, 2018
The former director that was once hailed for his gritty and dark portrayal of the source materials is currently attached to a few upcoming projects in the DCEU but only in the role of a producer. This includes the standalone Aquaman movie later this year, and Wonder Woman 2 and Suicide Squad 2 sequels next year.
It should be noted that voluntarily parting ways and being fired can often be confused. Hence, Snyder could have discussed his exit with the upper echelons before his announcement.
Regardless, Justice League was heavily criticized by the audience and the expensive project ended up as a disaster for the studio. That is not something that you want to leave behind before changing roles in the industry. The movie was an utter mess, half-baked, and nowhere near the levels of satisfaction that fans were seeking when purchasing their tickets.