Selecting a research topic should be out of interest and in line with the context of concern. That being said, you could check out the titles of MA theses rendered by the Department of Linguistics, at the University of Illinois Urbana-Champaign, so that you can grasp the current trends in researching TESOL. Below is the link.
Department of Linguistics. (n.d.). MATESL theses. Linguistics at Illinois. https://linguistics.illinois.edu/resources/libraries-and-reading-rooms/tesl-library/matesl-theses
I have already answered this question. I am going to copy and paste here again.
No one can suggest a better research topic for anyone for successful and effective research without your help - without understanding your area of interest and your competence in that academic area. Ask yourself:
1- What do you like the most in your academic field?
2- What can you do better than other in this area?
3- What are the main problems in this area?
4- Which problem[s] can you solve/want to solve/discuss in a better way?
Moreover, look at the previous topics of the researchers because they can help you. When you make a web of ideas and topics in such a way, you can bring out a better research topic according to your interest and competence.
The topic you are to specialize in must be interesting for you. At the same time I would try to fit it to a current problem in English teaching. I think you are on the good path now - the topic you are interested in seems relevant. I searched for YOU resources you might want to look at for new sets of idea:
1) Yang, S., Shu, D. & Yin, H. “Teaching, my passion; publishing, my pain”: unpacking academics’ professional identity tensions through the lens of emotional resilience. High Educ (2021). https://doi.org/10.1007/s10734-021-00765-w Free access:
Article "Teaching, my passion; publishing, my pain": unpacking acade...
2) Karim Sadeghi, Jack C. Richards (2021). Professional development among English language teachers: challenges and recommendations for practice, Heliyon Volume 7, Issue 9, Sept. 2021, Free access: Article Professional development among English language teachers: Ch...
3) Mahapatra, S.K. Online Formative Assessment and Feedback Practices of ESL Teachers in India, Bangladesh and Nepal: A Multiple Case Study. Asia-Pacific Edu Res (2021). https://doi.org/10.1007/s40299-021-00603-8 Free access: Article Title of the paper: Online Formative Assessment and Feedback...
4) Yelenevskaya, Maria & Ekaterina Protassova. 2021. Teaching languages in multicultural surroundings: New tendencies. Russian Journal of Linguistics 25 (2). 546–568. DOI: https://doi.org/10.22363/2687-0088-2021-25-2-546-568 Free access: https://helda.helsinki.fi//bitstream/handle/10138/331908/YelenevskayaProtassovaRUDN.pdf?sequence=1
I think you can write about any linguistic problem learners face when learning English as a foreign or a second language. You have to decide what is a real problem to foreign learners of English.