Problem Link.
I am facing Time Limit Exceed in this problem and I am not able to improve my code any further.
(The following code is in python, but I have even tried in same thing in C++ and got TLE for last test case.)

import sys
input = sys.stdin.readline # for fast input...
 
# graph input. n->no of nodes, m->no of edges...
n,m = map(int, input().split())

# constructing bidirectional graph...
# I am using '0' based graph indexing...
graph = [[] for _ in range(n)]
for _ in range(m):
	a,b = map(int, input().split())
	graph[a-1].append(b-1)
	graph[b-1].append(a-1)
 
g = 0 # g is an indicator variable, g->1 means "impossible". 

# degree of each node should be even for Eulerian cycle in undirected graph...
for i in graph:
	if len(i)%2:
		g = 1
		break
if g:
	print("IMPOSSIBLE")
else:
# using stacked method to find Eulerian path to avoid recursion (method link given)...
	stack = [0]
	path = []
	while stack:
		node = stack[-1]
		if len(graph[node]) == 0:
			path.append(node+1)
			stack.pop()
		else:
			nextNode = graph[node][-1]
			graph[nextNode].remove(node)  # I think this is the bottleneck because remove operation is not O(1).
			graph[node].remove(nextNode)
			stack.append(nextNode)
	if len(path) == m+1:
		print(*path)
	else:
		print("IMPOSSIBLE")

I have implemented the method from this Link of CP-Algorithms in my code.
Please read my code. I have mentioned what could be the bottleneck in my code, and I don't know how to overcome this problem. If I avoid removing edges from graph, then how should I track what edges not to visit.
Thanks in advance and If you want to help and don't understand what my problem is or anything else just comment for the same I would try to explain better what is my issue here.
Also you can simply comment some links or similar problems related to this so that I can do some further research.
Any kind of help is acceptable :)

https://cses.fi/problemset/task/1731 , Can someone please explain me how to approach this problem?

Below is the question link. https://cses.fi/problemset/task/1197 In this question I was thinking to get all cyclic paths and then go through all of them to get if any path has a negative value, if there is such a value then just print it and break the loop there itself. But I am having problem in printing all cyclic paths. :(