The search message feature doesn't work sometimes maybe for specific words and also doesn't if complete word is not searched for

Description:

Steps to reproduce:

1.Go To search messages option
2. Search for a message
3. Sometimes it works and sometimes not

Expected behavior:

It should work always for all words and even if an entire word is not searched should work for matching letters

Actual behavior:

1. Doesn't work for the word 'what'
   

2. Doesnt work for the word 'other'
   

3. Detects only if complete word is written and doesnt if only some letters are written

Here it doesn't detect for 'hell' or for anything shorter than hello , but will detect for hello (This bug is for all messages most probably )
Whereas some words are not detected for some reason

Server Setup Information:

• Version of Rocket.Chat Server: 3.12.0
• Operating System: Windows(WSL)
• Deployment Method:
• Number of Running Instances: 1
• DB Replicaset Oplog:
• NodeJS Version: 12.x
• MongoDB Version:4.x

Client Setup Information

• Desktop App or Browser Version:Browser
• Operating System: Windows

Additional context

I dont exactly know for which all words it doesnt work , the above were some examples which I tested

Relevant logs:

Reproduce message search in Rocket.Chat using the reported words “what,” “other,” “hello,” and partial terms such as “hell.” Compare the observed results with the expected matching behavior, then trace the message-search entry point to identify the responsible search path; done means searches consistently handle these cases as specified.