Hi Diksha,
Yes, sure these are pandemic days and all countries are making their own rules to save themselves from the spread of the disease.
In Ukraine, while coming from India or from UAE, they are asking you to have a valid COVID 19 test report with negative remarks, which should max 72 hours old, so try to get yourself tested within that time frame including travel time.
If you are coming through UAE, there is a scam at Dubai airport, as the airlines there, especially Fly Dubai, are not letting you board their flight, even if you have a valid (Your) government-approved Test report of negative covid. They will insist you get a test done at Dubai airport, which is extremely expensive, and extremely nerve-wracking if you want to board a connecting flight. The best part is to insist that as per WHO rules, reports produced by any government-approved covid centers taken within 72 hours should be honored, or they give it in writing that they do not accept the Government of India or any other government health reports in UAE. This will help you get through the hassle.
One more thing...be very careful to take hard copies of your tickets, boarding passes, connecting flights, and visa with you, as the airport staff (Again Fly Dubai) will ask you for hard copies, if you don't have it, they will charge a sum of around USD $20 to make the copies from their photocopier for you.
One more thing regarding UAE airport, if you are traveling on a budget airline, and your handbag is within 7 Kgs limit, and you have mistakenly bought some duty-free items you will have to pay for extra weight, as they have a weighing machine installed at the boarding gate, which includes your duty-free purchases also within the 7 Kg limit. Excess baggage is payable @ 15 USD per Kg. This happens on budget flights specially Go-Air, Vistara, Wizz Air, etc.
Hope these tips will be helpful for you to save some money.