Engagement delay, soft shifting

Hi everyone! New here and looking for some insight. 2017 SR5 4WD 104,000 miles. Ive had her three years-no issues. Regular oil changes-all synthetic as required. I crank her up this morning, shifted into drive and nothing. It usually starts moving before I accelerate, this morning it did not. Tapped the gas a bit, nothing, not even a rev of the engine. Put back into Park, then drive again-did the same thing. Third time, pushed the gas a little harder-a loud thud and then engaged into drive. No issues after that.
This happening made me overthink everything and anything that could be wrong or is it a precursor for something about to shit the bed!
I’ll add, she does soft shift between R and D, I hadn’t thought much of it until today. Could the issues be correlated?
Everything I’ve read keeps going back to low/dirty transmission fluid/line? How about the battery, if it were going bad could that cause shifting/engagement issues?
I welcome any insight.

 

https://www.4runners.com/threads/in...ty-low-transmission-fluid….46419/#post-759414

 

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