Uneasy about his ex gifts

So my partner and is ex gf have bewn seperated for 4.5 years. She hates my guts because she is not quite over hin, still starts argument about from back in the day and finds fault in me whereever.

However, im not a jealous person but sometimes shr makes me feel soooo uncomfortable.
Qhen they argue, she always blackmails him with their daughter (now 5.5 yo) and then out of nowhere she will start trying to be nice to him again. On fathersday, birthdays and christmas, he gets showered with gifts. For fathersday i bought him pjs from peter alexander and made him a photobook. She send a massive parcel with expensive brand shoes, cap, shirt, boxershorts, a set oh peter alexander pyjamas and a photobook with pictures of my social media involving him and simply cutting me out. She always writes a letter saying ita from the little one.

When the little one is here and ther eis an occasion, i let her pick soemthing. She would always go for candles or a glassball or a cup, or something silly but its picked by her and she also draws pictures.

Now mum and dad had an argument the otherday again about her being upset that he found me too soon and bla bla

So today, three weeks later, he receives a parcel. Again apprently picked by the little one. A pair of $130 boots, a brand boxershorts and shirt, i guess u could call it a pyjama worth easy $70

She always says she has no money even thought she spends it on her self a lot, maybe she cant deal with money but i feel auper uncomfortable that she always buys him things like that. Sorry the little one apparently picks them. Never ever would she pick a nightiebor a shirt for her mum when i ask her to pick something and i dont know how to deal with it. Its not that she is a competition but him sitting there with those boxers on ahhh it annoys me. And im sorry i find it creepy. So many gifta to pick and know its not picked by their daughter. It pisses me off. What to do? Just ignore it? Wonder if i should send her a night dress and some Hotpants. Ha

EDIT
THE ARGUEING is usually about that she always threatens to tell the little one what an idiot he was in their relationship and how upset he mad eher and that he is the reason why they arent a happy fanily, and apaprently sometimes she cries at home and tells her that she is crying because of her dad (i think she is really struggling to move on and see him happy with another woman) so he argues with her to not involve their personal business with the child and make him look bad. She then would threaten him to fight in court about giving him less days with his daughter custody wise and she has legal aid, he has to pay for a lawyer and the money isnt there (not eligible for legal aid) . So thats what the arguments are usually over and her saying 'poor me i dont have a happy family like you' its a very difficult situation i know but how to set boundaries without jeopardising the relationship with his daughter